You do have the cable from the modem connected to the 'wan' port on the back and the computer connected to one of the lan ports, right?
Try turning the modem and the router and your computer off, then turn them on modem first, wait half a minute, then router, wait half a minute, then the computer.
If that doesnt work, try a factory reset on the box (see the manual, theres a little button on the back) and then try to connect via the LAN port like you have it set up now. If that doesnt work, try the "ez setup" instructions (again, different little button on the back).
Be fearful when others are greedy, and greedy when others are fearful. Just another form of "buy low, sell high" for those who have trouble with things. This rule is not universal. Do not buy a 1973 Pinto because everyone else is afraid of it.